In a patent infringement case that RIM was probably watching carefully, a federal judge in Boston granted an injunction on Monday against Boston Communications Group Inc., which sells customer management services for prepaid wireless telephones to a number of companies, including Cingular and Alltel Communications Inc.

The court had previously ruled that Boston Communications had infringed on two patents held by Freedom Wireless Inc., and has awarded Freedom Wireless $128 million in damages. Under the injunction, wireless companies that use the BCGI prepaid wireless services must stop selling them. The companies have 90 days to continue serving current customers, during which they must pay royalties to Freedom Wireless.

BCGI said that the injunction could affect service to 3.1 million prepaid customers, including 400,000 at Cingular, representing 70 percent of its total revenue. BCGI plans to appeal the injuction.